Leveraging sub-E0 dose assessment methodology to improve EUV lithography cluster dose performance

The effective dose delivered by an EUV lithography cluster is composite function of the dose provided by the scanner EUV radiation source and illuminator, the reflectance of the EUV mask, the transmission of the scanner projection optics and the PEB conditions experienced by the EUV sensitive imaging resist. Open frame test wafer exposures and the sub-E0 analysis technique described at SPIE2018 have been adopted to characterize and monitor the impact of the factors above on the effective dose stability and uniformity. Wafer exposure sequences and layouts, and the details of the analysis methodology were customized to study adverse dose factors in each of the areas described above.